The Expression Of PPTA MRNA In The Rat Trigeminal Ganglion In Response To Various Initial Orthodontic Forces

Both patient and clinician have been troubled by orthodontic pain during the initialphase.Searching for how orthodontic pain takes place and changes, and investigatinghow to relieve or prevent it are hot spots all the time. Substance P (Substance P, SP) isrecognized as one of the maxillofacial major pain transmission mediums, and PPTA isthe precursor of SP. The changes of SP and PPTA mRNA in the trigeminal ganglion hadbeen confirmed during tooth movement. However different orthodontic force effects onSP and PPTA mRNA in trigeminal ganglion had not been reported. In order to observethe changes of PPTA mRNA in rats’ trigeminal ganglion with various initial orthodonticforces,SP was used as the pain marker in our study.The relationship betweenorthodontic force and orthodontic pain was discussed in this paper. The results are asfollows:1Establishment of animal model and experimental group7-9weeks male SD rats were used as experimental animal.Set the nickel titaniumcoil spring boosting device between the same side of the maxillary first molar and theincisor, and reinforce it by self-curing plastic. SD rats were randomly divided intocontrol group and experimental group, experimental group according to differentorthodontic force was divided into20g group,50g group and80g group. To set time (2h,1d,3d,5d,7d), kill the rats and obtain the trigeminal ganglion,then frozen in liquidnitrogen.2Extraction of PPTA mRNA and design of PPTA mRNA primers It was success to extract total RNA in rats’trigeminal ganglia by Trizol method,which would lay the foundation for follow-up experiments.The design of the primer isreferring to the related literatures, the design of the primer sequence is as follows: PPTA:upstream primer5’-TTCCACTCAACTGTTTGCAG-3’; downstream primer5’-GTAGT TGTGC ATTGC TCTTC-3’.3The dynamic changes of PPTA mRNA in the rats’trigeminal Ganglion with variousinitial orthodontic forcesRT-PCR confirmed that:(1)The expression of PPTA mRNA in rats’trigeminalganglion at different time points showed no significant changes in the control group(p>0.05),but the expression of PPTA mRNA in the experimental group were strongerthan that in control group at all the time points and had certain regularity. PPTA mRNAlevel was increased after2hours and reached the peak level around3days during toothmovement,7days after tooth movement PPTA mRNA level was still higher than that inthe controls(p<0.05).(2) The dynamic changes of PPTA mRNA in rats’trigeminalganglion of20g group was similar to that of50g group and no statistically significantdifference was found between the two groups at each time point (p>0.05).But theexpression of PPTA mRNA of80g group was significantly higher than the other twogroups at each time point (p<0.05), and the peak of expression was relatively advanced.